近50年南海西沙地区的气候变化特征研究

采用西沙台站1958~2005年基本气象观测资料,系统分析西沙地区近50a来主要气象要素(温度、降水、风速、日照和云量)变化特征。结果表明,近50a来年均地面气温增暖幅度约1.0℃,增温速率0.19℃/(10a),与全国平均的增温率接近。四季的平均气温也都呈上升趋势,其中冬季和春季的上升趋势最明显,秋季次之,夏季的变化最小。降水的波动性很大,年降水量变化趋势不明显,四季中只有春季降水呈明显增加趋势。地面风速主要呈减小的趋势,特别是在近30a年平均风速比常年值明显偏小。四季风速均减小,尤其在秋、冬季。年日照时数、总云量均呈显著下降趋势,而低云量略有增加。

Features of Climate Change over the Xishan Island over the South China Sea in Recent 50 years

In this paper, the features of climate change over Xisha in recent 50 years have been systematically examined by using the basic meteorological data in 1958-2005. The results showed that annual mean surface temperature rose by about 1.0℃, with a warming rate of approximately 0.19℃/(10 a), which is close to the average value of whole country. The seasonal mean temperature was also on the rise, with the most obvious ascending trend in winter and spring. The annual precipitation had a big fluctuation and no significant trend was seen. For seasonal precipitation, only spring had obvious linear ascending trend. The surface wind speed had a significant trend to decrease, especially in recent 30 years the annual mean wind speed was smaller than the normal year. The wind speed in four seasons also had significant decrease, especially in autumn and winter. Also, the annual sunshine duration, total cloud amount took an significant decreasing trend, while the low cloud amount had a bit increase.